The Chain by Adrian McKinty - final

It's something parents do every morning: Rachel Klein drops her daughter at the bus stop and heads into her day. But a cell phone call from an unknown number changes everything: it's a woman on the line, informing her that she has Kylie bound and gagged in her back seat, and the only way Rachel will see her again is to follow her instructions exactly: pay a ransom, and find another child to abduct. This is no ordinary kidnapping: the caller is a mother herself, whose son has been taken, and if Rachel doesn't do as she's told, the boy will die.